Apparatus for printing upon coated surfaces



Aug. 11, 1964 H. E. H. RASKIN ,3

APPARATUS FOR PRINTING UPON COATED SURFACES Filed Feb. 20, 1959 flusmr [000420 flawk/ PAM/m United States Patent 3,144,355 APPARATUS FOR PRINTING UPON COATED SURFACES Hubert Edouard Henri Raskin, 88 bis Rue Adrien Lemoine, Pontoise, France Filed Feb. 20, 1959, Ser. No. 794,618

Claims priority, application Belgium Feb. 21, 1958 2 Claims. (Cl. 11844) The present invention relates to an apparatus and process for printing upon coated, laquered or varnished surfaces, hereinafter all referred to as lacquered surfaces, and the like. The term printing, moreover is used in its generic sense to connote designs as well as characters and numbers.

Various processes have been proposed and employed for printing lacquered surfaces and the like of many different surface configurations with the use of half-tone plates or printing rollers. One of the very numerous uses of such techniques is in preparing advertising layouts. One of the major inconveniences with such priorart printing processes, however, resides in the fact that the printing itself, as applied to the surface to be decorated, has a definite thickness, especially if a plurality of printing steps are performed, as in multi-color printing. At the junction between two colors of a printed design, moreover a super-position of the printed colors often occurs over a limited width giving rise to unaesthetic and disturbing raised regions. While techniques have been evolved for printing without leaving a raised surface, such techniques necessitate a previous application of a priming coat to the treated surface and, furthermore, are only applicable to fiat or planar surfaces.

An object of the present invention, accordingly, is'to provide a new and improved apparatus and process for printing that obviates the above-described difficulties. The invention provides for the printing of lacquered surfaces and the like, whether of planar configuration or not, and whether continuous or not, without producing raised regions and without requiring supplementary protective layers or priming coatings.

In summary, the process underlying the invention involves applying to the lacquered surface or the like, a printing paste made up of a solution of dye, a solvent, an acid, depending on the lacquer or other coating of the surface, and a medium whose viscosity is controlled in terms of the degree of softening of the aforementioned lacquer and the like. The lacquer and the like is softened in such a way as to allow for impregnation therewithin by the dye of the printing paste, but without raising the temperature to that of polymerization of the said lacquer or the like. The said medium is then disposed of by washing, leaving the printed design absolutely clear, after which if necessary the surface is raised to the temperature of the polymerization of the lacquer and the like and is dried and then subsequently permitted to cool.

As an example of a complete manufacturing process embodying the invention, which is to be considered as illustrative only of one of many possible applications of the invention, consider the manufacturing of a thin 03 mm. aluminum strip of width 60 cms. that is to be formed into imitation tiles stamped in relief and decorated with a red colored motif, the grooves delineating the tiles being colored black and having a deepness of 2 mm.

The laminated aluminum strip may be provided in rolls of from 100 to 3000 or more meters in overall length, as shown at 1, FIG. 1, mounted on the wind-off device 2. The strip material 3 itself is then led through a conventional cleansing, degreasing and parkerising plant 4, being thereafter dried, as by hot air, at 5. The

' not impossible.

strip is then coated with an Epikote resin, lacquer or other material, at 6, as with the aid of coating cylinders 6 or spraying, not shown. An oven '7 bakes the coating, after which the strip is cooled, as by cold air at 8, and re-wound again upon a roll 9. The first manufacturing stage is thus achieved.

A roll of such coated strip is shown at 10 in FIG. 2 mounted upon the wind-off device 11. The strip is led through a conventional printing machine 12 which prints the before-mentioned red motifs and black grooves, as before explained and as hereinafter more fully discussed, an oven 13 where the impregnation of the coating by the two colors, red and black, takes place, and through a cooling blast 14.

The wiping and cleansing of the remaining paste is achieved through friction by, for example, blotting paper 15, which is drawn against the strip in the opposite direction to the motion of the strip, as indicated by the arrows. The before-mentioned grooves may then be stamped by two metal or any hard cylinders 16, 17, engraved with the motifs to be stamped; one male and one female, as shown. The speeds of the printing rollers 12 and that of the stamping cylinders 16, 17 are made identical, as by synchronously coupling them together, schematically indicated at 20. Their relative positions are initially set so that the red motifs will fall between the black lines delineating the tiles, and the stamped grooves will correspond exactly to the black lines. The strip will thus flow through the printing and stamping plants 12, 16, 17 in one and the same movement, without any problems of registration of the patterns. This would not, however, have been so, had the printing and stamping operations been done separately or non-synchronously. In such a case, the variations in the length of the strip due to its elasticity and eventual differences of temperature would render the correct registration of different printed and stamped patterns very difilcult, if If necessary, the thus decorated and stamped aluminum strip can then be raised to polymerization temperature of the lacquer and the like and dried or hardened, as at 21. The strip is then allowed to cool and is wound up in a finished roll 18, which can have any desired length. A protecting paper sheet 19, may be interleaved between the adjacent windings of the coil 18 in order to protect the finished surface.

The obtained lining is easy to apply, can be cut with ordinary scissors, takes little storage space, is very light (800 grams per square meter) and can easily be handled and transported. As an example, a 25-meter long roll only has a diameter of 30 cms.

In accordance with the invention, the softening of the lacquer or other surface coating is effected by making the said surface pass through an atmosphere saturated with the vapors of a solvent, by heating, or by both of these two methods together. InFIG. 2, following the application of the novel later-discussed printing paste or ink of the present invention at printing station 12, the oven 13 raises the temperature of the lacquer or other coating on the strip to permit its impregnation by the dye of the printing paste. That temperature will, in general, be

greater than room or ambient temperature, butless than the temperature required for the polymerization of the lacquer and the like. Thus, for a glycero-phthalic lacquer and the like the polymerization temperature of which is betwene C. and C., the temperature of the oven 13 will be adjusted to between approximately 50 C. and 70 C. Under such circumstances, it has been found, as before stated, that the dye in the printing paste will impregnate the softened lacquer and the like. This process will generally occur in a time interval ranging from a few seconds to a few minutes. After cooling at 14, the medium or vehicle of the printing ink or paste is wiped away as at 15, so that the decoration or other printing is all below the outer surface of the lacquer and the like. Raising the temperature at 21 to the polymerization temperature of the lacquer and the like results in polymerizing the coating, which, after drying and hardening is then allowed to cool, being ready for use.

While the theory of how the above-mentioned impregnation takes place is quite complicated, it appears that the presence of heat of the proper value at 13 softens not only the lacquer and the like, but the ingredients of the later-detailed printing paste, including, for example, oleic acid, or equivalent materials. These materials then appear to react upon the outer surface of the lacquer or other coating permitting the dyes to impregnate the same in what is believed to be a type of molecular diffusion. It is experimentally observed that there is no significant alteration of the lacquer surface coating, however, because, after cooling, it regains the high glossy appearance that it initially had prior to coloring.

Whether this explanation is or is not absolutely correct, however, it is sufficient to describe the invention as it has been found to work in practice. A typical printing paste composition so found to work is:

Grams Oleic acid 1 5 Printing wax (I. G. Farben) Dye Mineral oil of high boiling point 850 Heavy grease of high boiling point 100 The dyes that can be used are generally of synthetic nature, preferably aniline base dyes resistant to light. They should be soluble in oils. The heavy grease medium or vehicle keeps the dyes in their place without smudging, its high viscosity at high temperature preventing the whole paste from running even if the printed surface is heated while in a vertical or oblique position.

The printing paste must be perfectly kneaded so that it is homogeneous and possesses sufficient penetrating strength to assure a good impregnation of the lacquer or other coating upon the surface to be treated.

Among the lacquers or other coatings suitable for receiving printing in accordance with the invention are materials of organic and/or synthetic nature, such as the well-known commercial varnishes and lacquers (glycerophthalic, nitro-cellulose, nitro-synthetic, epoxy, ureaformal, vinylic, isocyanates, etc.) coated upon any supporting surface whatsoever (metal, wood, wood fibers, cement, etc.) capable of resisting heat in the oven 13 up to 60 C. or more, for a short time, ranging from a few seconds to a few minutes; or on plastic sheets of any nature such as polystyrene, vinyls, polyethylene, polyesters, etc. Such coatings are all more or less impervious, once dried and hardened.

The process underlying the invention thus assures that the printing is incorporated into the lacquer or the varnish of the surface to be treated; the risk of flaking and of erasure by rubbing, particularly in the case of multiple printing, is avoided. This is a great advantage in and of itself and precludes the deterioration resulting from handling, storing or transporting. The manufacturing cost of the surface-to-be-printed, in addition, is lessened inasmuch as the present invention does not necessitate the application of a protective varnish.

It is, of course, evident that this invention has been described in terms of illustrative examples and many modifications of detail can be made without departing from the scope and spirit of the invention. In particular, the percentages of the composition of the printing paste are open to some variations; the essential point is that the paste be absolutely homogeneous and that its penetrating 4 strength be adequate for the given lacquer or varnish, in accordance with the criteria above-presented.

Not only does the present invention eliminate the raised surfaces and other disadvantageous features, before discussed, but, prior to the temperature treating that effects impregnation of the dye into the coating of lacquers or the like, the printing paste or ink may be wiped off in the event of a mistake, without marring the surface. This eliminates any waste of product. The obviating of buildup or raised surfaces, moreover, also serves to reduce maintenance costs and wear upon the printing tools, such as the silk screens, rubber stamps, metal rolls, etc. employed at station 12. Because the printing paste or ink of the present invention does not dry at room or other ambient temperatures, furthermore, no clogging of the apparatus takes place. The printing apparatus, indeed, may be abandoned in the state it has last been used, and it can be promptly put into operation after several weeks shut-down without maintenance.

If desired, moreover, the male stamping or engraving cylinder 16 may also print the black or other color in the engraved grooves, thus simplifying the printing apparatus 12. In the case of printing only in embossed surfaces, indeed, one can eliminate the separate synchronous printing apparatus 12 through its effective combination with the cylinder 16. All that would be necessary, of course, would be to have an inking roll, not shown, supplying ink or paste to the cylinder 16, as is well known. The temperature elevation and hardening steps would then follow the station 16, 17.

What is claimed is:

1. Apparatus for printing upon a polymerizable lacquered surface, that comprises, means for applying to the said surface a homogeneous paste comprising printing dye, solvent and a paste medium of sufficient viscosity to resist substantial impregnation of the lacquered surfaces when the same is heated to soften it; means for thereupon heating the lacquered surface to a degree sufficient to permit impregnation therewithin of the said dye but insufiicient to permit of polymerization of the lacquered surface; means for removing the said paste medium; and means for raising the temperature of the surface to the temperature of polymerization of the lacquered surface.

2. Apparatus for printing upon a polymerizable lacquered surface, that comprises, means for applying to the said surface a homogeneous paste comprising printing dye, solvent and a paste medium of sufiicient viscosity to resist substantial impregnation of the lacquered surfaces when the same is heated to soften it; means for thereupon heating the lacquered surface to a degree sufiicient to permit impregnation therewithin of the said dye but insufficient to permit of polymerization of the lacquered surface; means for removing the said paste medium; means for raising the temperature of the surface to the temperature of polymerization of the lacquered surface; and means operating synchronously with the applying means for stamping predetermined regions of the said surface.

References Cited in the file of this patent UNITED STATES PATENTS 1,516,598 Griffiths Nov. 25, 1924 2,403,084 James July 2, 1946 2,622,991 Sturm -2 Dec. 23, 1952 2,625,064 Brown Jan. 13, 1953 2,866,711 Hart Dec. 30, 1958 2,879,168 Hunter Mar. 24, 1959 2,906,590 Evans Sept. 29, 1959 

2. APPARATUS FOR PRINTING UPON A POLYMERIZABLE LACQUERED SURFACE, THAT COMPRISES, MEANS FOR APPLYING TO THE SAID SURFACE A HOMOGENEOUS PASTE COMPRISING A PRINTING DYE, SOLVENT AND A PASTE MEDIUM OF SUFFICIENT VISCOSITY TO RESIST SUBSTANTIAL IMPREGNATION OF THE LACQUERED SURFACES WHEN THE SAME IS HEATED TO SOFTEN IT; MEANS FOR THEREUPON HEATING THE LACQUERED SURFACE TO A DEGREE SUFFICIENT TO PERMIT IMPREGNATION THEREWITHIN OF THE SAID DYE BUT INSUFFICIENT TO PERMIT OF POLYMERIZATION OF THE LACQUERED SURFACE; MEANS FOR REMOVING THE SAID PASTE MEDIUM; MEANS FOR RAISING THE TEMPERATURE OF THE SURFACE TO THE TEMPERATURE OF POLYMERIZATION OF THE LACQUERED SURFACE; AND MEANS OPERATING SYNCHRONOUSLY WITH THE APPLYING MEANS FOR STAMPING PREDETERMINED REGIONS OF THE SAID SURFACE. 